The weakest level of property sales in four years is pushing down house prices in all regions of the UK outside London, says the body representing estate agents.

The monthly snapshot of the property market from the Royal Institution of Chartered Surveyors found that home transactions in July dropped for a fourth month and the balance of surveyors reporting falling prices was at its highest level for a year.

RICS said its members expected prices to continue edging downwards over the coming months even though they are hopeful that the number of sales will increase in the second half of 2012.

Asked about the trend in prices over the past month, a balance of -24 percentage points of agents said they were falling. The figure in June was -22 points.

RICS found that most surveyors reporting price falls said they were down by less than 2%, but said there was a distinct north-south divide with London prices rising and downward pressure weakest in the south-east.

Peter Bolton King, RICS's global residential director, said: "Despite the terrible weather seen in many parts of the county last month, a steady number of potential buyers still got out there to test the market. However, this didn't result in a higher level of actual transactions. Fewer sellers are putting their homes up for sale and the ongoing problem of accessing affordable finance is not helping. If vendors want to sell their homes quickly, they will have to be realistic in their price expectations."